Bulletin of the American Physical Society
Joint Fall 2013 Meeting of the Texas Sections of the APS, AAPT, and Zone 13 of the SPS
Volume 58, Number 10
Thursday–Saturday, October 10–12, 2013; Brownsville, Texas
Session D1: Poster Session (4:00 - 6:00) |
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Chair: Michael Sadler, Abilene Christian University Room: Gran Salon |
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D1.00001: Structural Integrity of ssDNA on the Surface of Solid-state Nanopores Mohammed Arif Mahmood, Waqas Ali, Ashfaq Adnan, Samir Iqbal Self-assembly and 3D conformation of nucleic acid aptamers enable selective binding with biomarkers and cells. One mode of utilizing selective property of the aptamers is by grafting these in solid-state nanopores. Coating the inside walls of the nanopores with protein specific nucleic acid aptamers changes the energy landscape and affects the biomarker translocation. When the target protein passes through the nanopore, it interacts with surface-bound DNA and the process alters overall energy profile, which is essentially specific to the protein detected. The simulations showed that fundamental challenges in this process were to ensure these detection motifs held their structure and functionality under applied electric field and experimental conditions. The all-atom molecular dynamics simulation of the effects of external electric field on the 3D conformation of such ligand-DNA demonstrated how the grafted moieties affected the translocation time, velocity and the detection frequency of the target molecule. A novel case of protein translocation was also investigated for comparison where DNA was pre-bound to the protein. [Preview Abstract] |
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D1.00002: How to get more students in physics Samina Masood Physics programs are slimming down. Not many students are attracted to physics program any more. We identify some of the key factors that play key role in the loss of students. We also propose a few steps to motivate students to increase the physics enrollment. [Preview Abstract] |
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D1.00003: Analysis of Atomic Spectra with applications to solar measurements Keeley Townley-Smith, Sara-jeanne Vogler, Cristian Bahrim Atomic and molecular spectroscopy allows us to reveal the constituents of matter. Using PASCO{\textregistered} equipment we analyze the emission lines of several components of air such as oxygen, hydrogen, nitrogen, carbon dioxide, water, and helium. The pressure broadening on the emission lines allows us to enlarge them to a few nm in width and thus, to well resolve the lines. The characterization of the emission lines is applied to unknown compound spectra to identify the atomic constituents present. Also, the information can be further used to identify absorption lines embedded in the emission spectra of a known blackbody source of radiation: indeed the profile of the emission lines and their location should coincide with the absorption lines. The dominant absorption lines are from the ground atomic state. We attempt to apply this knowledge to de-convolute the absorption lines from the blackbody spectrum of the Sun modified by the absorption lines of Hydrogen and Helium atoms located in the Sun's corona, and of Nitrogen, Oxygen, Carbon and other atoms from the Earth's atmosphere. [Preview Abstract] |
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D1.00004: Modeling of Light Propagation and Optical Aberrations with Ray Tracing and Gaussian Beams Satzhan Sitmukhambetov, Malik Rakhmanov We built a model to understand light propagation through optical systems using ray tracing and Gaussian beam techniques. We use it for analysis of various optical systems including lenses, mirrors, interferometers, and laser resonators. We do not make paraxial approximation in our ray tracing algorithm. Therefore, the model can be used to study common optical aberrations, such as spherical aberration, coma, or astigmatism. Also, we can use the model to analyze natural optical phenomena, such as rainbow. The model is a useful tool for research and educational purposes. [Preview Abstract] |
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D1.00005: Stochastic Optimization Techniques on Parameter Estimation of Binary Inspirals: Particle Swarm Optimization and Genetic Algorithm Shihan Weerathunga, Soumya Mohanty The search for gravitational wave (GW) signals from inspiraling compact object binaries is performed ~using matched filtering on GW detector data. Numerical maximization is applied over a set of matched filter outputs to estimate signal parameters. The noisy nature of the data and the large number of signal parameters lead to a highly multi-modal and high dimensional objective function. This precludes the use of deterministic locally convergent optimization algorithms and a plain grid search is computationally prohibitive for even a modest number of signal parameters. Stochastic optimization methods can be used to efficiently find optimal solutions in such situations. We are engaged in a comprehensive study of the performance of two popular stochastic optimization algorithms, Particle Swarm Optimization and Genetic Algorithm, on the GW matched filtering problem. Results are presented here for~a two dimensional testbed binary inspiral problem. Studies of higher dimensional problems are in progress. [Preview Abstract] |
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D1.00006: Pulsar Timing Simulator for the testing of Gravitational Wave Analysis Pipelines Jing Luo, Fredrick Jenet We are developing a pulsar pulse time-of-arrival simulator based on SPICE, the solar system ephemeris software package developed at NASA's Jet Propulsion Laboratory. Currently, the analysis and simulation of pulsar timing data has been predominantly carried out using either the TEMPO or TEMPO2 software packages. This completely TEMPO-independent simulation will enable full end-to-end testing of these packages as well as the data analysis pipe-lines based on these packages. This includes pipe-lines that will be used to detect and study gravitational waves. This poster describes the current design of the new package, its capabilities and limitations, and well as the results of preliminary tests of the TEMPO2 package. [Preview Abstract] |
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D1.00007: Searching for accreting white dwarfs, black holes, and neutron stars within\textit{ Swift} ultraviolet counterparts to \textit{Chandra} X-ray sources in the Galactic Bulge Survey region Catherine Fielder, Thomas Maccarone, Robert Hynes The \textit{Swift} portion of the Galactic Bulge Survey (Jonker et al. 2011) surveyed random sections from the northern strip of the Galactic plane (1$^{\circ}$ \textless\ $b$ \textless\ 2$^{\circ}$ ) in the direction of the Galactic center. By avoiding the center of the Galaxy extinction is much more limited while still maintaining a relatively high source density. The source list was originally compiled by \textit{Chandra} in the X-ray. We are searching for CVs, and possibly LMXBs, but coronally active stars and other hot stars may be detected. All of the detections in the UV are expected to be foreground objects. Some of the overall goals of the Galactic Bulge Survey are to 1) Constrain the Neutron star equation of state, 2) constrain the black hole mass distribution, and 3) constrain X-ray binary formation scenarios, all of which can be accomplished through source-type population numbers and making detailed follow-up observations of the X-ray binaries in order to better understand their distribution. The goal for this segment of the project is to match the UV observations with X-ray sources from \textit{Chandra} and to then classify these sources. A total of 50 out of about 1200 sources were matched in the UV, which is not unusual considering the \textit{Swift} coverage was less than half of that of \textit{Chandra}. 8 of these sources have noticeable UV excess and 3 of these sources seem to vary. [Preview Abstract] |
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D1.00008: Looking for Periodicity in X-Ray Emission Data Andres Cuellar, Stephanie Cohen, Matthew Benacquista X-Ray Binaries are systems in which matter falling from one component of the system to the other releases energy in the form of X-Rays. We created an algorithm which uses Pearson's Chi-Squared test to look for periodicity in X-Ray emission data from NASA's Swift Burst Alert Telescope (BAT) 58-Month Hard X-Ray Survey. We use the known High Mass X-Ray Binary J1647.9-4511B to verify the accuracy of our program testing over a range of periods, bins and energy bands to verify the true period. Results are discussed. [Preview Abstract] |
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D1.00009: Examining XMM Observations in the Galactic Bulge Survey Region Vicente Estrada-Carpenter The VXMM catalog was created in an effort to find help find low mass X-ray binaries (LMXBs) as part of the Galactic Bulge Survey (GBS). VXMM consists of XMM-Newton observations made in the GBS region, two 6x1 degree regions 1 degree above and below the galactic plane. The goal of the project was to find GBS X-ray sources that exist in XMM observations in order to classify them. The XMM data was downloaded from NASA's database. Source detection was conducted on the filtered data sets using the 2-XMM Serendipitous Survey as a guideline for the procedure. The sources detected make up the VXMM catalog, which was used to cross reference with the GBS catalog to find GBS sources in the XMM data. In total the VXMM catalog found 107 GBS sources in the data. The spectra of several of these sources were examined to see which could be classified in the time available. CX13 was picked as it was the brightest GBS source not classified that was present in the data. CX13 was determined to not be an active star as its temperature would to be high. Using a power-law model fit LMXB was ruled out, as was background AGN after the power spectrum was analyzed. Leaving it to most likely be a cataclysmic variable. [Preview Abstract] |
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D1.00010: Determining the Relativistic Spin of the Black Hole Cygnus X-1 Sebastian Gomez, Michael Nowak Cygnus X-1 is a very well studied black hole in a high mass X-ray binary system. In order to have a complete description of a black hole one needs to know its mass and spin. The mass and spin of Cygnus X-1 have been measured to be $\sim$14.8 M$\odot $ and a* \textgreater\ 0.95, respectively. The problem is that there is a dust cloud in the line of sight to Cygnus X-1. This dust cloud scatters the X-rays from the source creating a dust halo around the source. This could affect the previous measurements of black hole spin. We improved upon previous studies of the spin by modeling the dust halo that lies in front of the system with the use of the ISIS and MARX software analysis packages. We analyzed 2011 data from the Chandra and RXTE telescopes from when the system was in the high/soft, accretion disk dominated, state. The data fits well with a multi-temperature blackbody, a broken power law and a beta source function that was used to describe the dust halo. All of our fits yielded similar results, with spin values of a* \textgreater\ 0.9. Accurately knowing the spin of Cygnus X-1 could give us insight into jet formation around black holes and when and how this black hole was formed. [Preview Abstract] |
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D1.00011: Variable Star Search Using ROTSE-I Data Isaac Guerra, Robert Kehoe We present results of a variable star search using data from the Robotic Optical Transient Search Experiment-I (ROTSE-I) telescope. Variable stars fluctuate in brightness as seen from Earth due either to intrinsic changes in the star's brightness or to extrinsic changes in the amount of the star's light that reaches Earth. Our research is focused on analysis of the time variation of optical light output as recorded in ROTSE-I images. Specifically, we are attempting to identify short-period variable star candidates which have amplitude variations on the order of one magnitude and periods on the order of several hours. For each candidate analyzed, we plotted a light curve and examined the shape to determine the type of variable. We also use a grouping, filtering, and averaging (GFA) algorithm that will help us reduce the error in the data taken by the telescope. Then to determine the period and amplitude of variation, we phased observations of the candidate from multiple nights into one plot using a cubic spline fit. We report on the confirmed discovery of a previously unidentified contact binary star: ROTSE1 J112431.65$+$460702.7. This star is now listed in the International Variable Star index (VSX) maintained by the American Association of Variable Star Observers (AAVSO). [Preview Abstract] |
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D1.00012: Kozai mechanism and the dynamics of highly inclined planetary orbit in HD 196885 binary system Suman Satyal, Billy Quarles, Tobias Hinse, Joaquin Noyola About 1/3 of the stars in the Milky Way are believed to be in binary; however, among the confirmed 905\,\footnote{http://exoplanetarchive.ipac.caltech.edu/index.html} exoplanets only 7{\%} are found to orbit binary stars. Depending on the orbits around the host star(s) a planet could be S-type, orbiting either one of the binary, or P-type, orbiting both of the binary. We have studied the dynamics of an S-type planet in HD 196885 AB considering the perturbation due to the secondary companion and with an emphasis on higher orbital inclination ($i_{pl})$ within the binary plane. Mean exponential growth factor of nearby orbits (MEGNO) maps are used as a chaos indicator to determine regions of likely orbital stability for the various choices of $i_{pl}$, semi-major axis and longitude of ascending node ($\Omega )$. Based on our analysis we have quantitatively mapped chaotic and quasi-periodic regions of the system's phase space. By inspection of the resonant angle we study the qualitative behavior of the argument of periapsis and find it to librate or circulate as a consequence of Kozai oscillations. Also, based on our stability analysis, an attempt has been made to constrain the possible higher mass limit of the planet and improve upon the current ephemeris with a more consistent dynamical model. [Preview Abstract] |
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D1.00013: Matching Black Hole Merger Waveforms Jose McKinnon, John Baker, Philip Graff Matched filtering techniques require accurate waveform models to perform precise parameter estimation. We present a hybrid gravitational waveform model for the inspiral and coalescence of non-spinning black-hole binaries. Since numerical-relativity (NR) waveform calculations remain computationally expensive and so cannot be used to investigate the complete space of possible parameters, we have combined effective-one-body (EOB) and post-Newtonian (PN) waveforms to produce a ``complete'' inspiral-merger-ringdown quadrupole waveform for use in the identification of systematic biases in parameter estimation of binary black-hole mergers. The approach is based on both frequency-domain (FD) and time-domain (TD) matching, and the minimization of systematic errors that arise from the matching process. In this work we have used various PN template families, such as the TaylorT1, TaylorT2, TaylorT3, TaylorT4 and the TaylorF2, together with the EOBNR (2,2) mode. Here we give results of the waveform matching technique and its efficiency for the different waveform models. [Preview Abstract] |
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D1.00014: Optical Photometry of BY Cam Modeled Using a Multipolar Magnetic Field Structure John Morales, Paul Mason, Andrey Zhilkin, Dmitry Bisikalo, Edward Robinson We present new high-speed broad-band optical photometry of the asynchronous polar (magnetic cataclysmic variable) BY Cam. Observations were obtained at the 2.1-m Otto Struve Telescope of McDonald Observatory with 3s integration times. In an attempt to understand the observed complex changes in accretion flow geometry, we performed full 3D MHD simulations assuming a variety of white dwarf magnetic field structures including both aligned and non-aligned dipole plus quadrupole field components. We compare model predictions with photometry and various phases of the beat cycle and find that synthetic light curves derived from a multipolar field structure are consistent with the optical photometry. [Preview Abstract] |
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D1.00015: High Speed Optical Photometry of the LMXB UW CrB: An improved Limit on the Orbital Period Derivative Jacob Segura, Paul Mason, Edward Robinson We present new broad band optical photometry of the low mass X-ray binary (LMXB) UW CrB on four consecutive nights in June 2013. These data were obtained at the 2.1-m telescope of McDonald Observatory and have a time resolution of 10s and cover a bit more than one orbital cycle each night. The light curves display partial eclipses of the accretion disk by the donor star that vary both in depth and orbital phase in the same manner as has been previously reported. Analysis of the new eclipse times in conjunction with published eclipse timings are well fitted with a linear ephemeris. We derive an upper limit on the time derivative of the orbital period, based on the best fit quadratic ephemeris, and discuss its implications on the average mass transfer rate. By including the newly observed type I bursts with published bursts in our analysis, we find that bursts are not observed between 0.93 and 0.07 phases, i.e. they are not observable during partial eclipses of the disk. [Preview Abstract] |
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D1.00016: Thermodynamics and kinetics of single stranded DNA (ssDNA) binding proteins Nabin Kandel, Amhed Touhami The aim of the present research project is to probe the thermodynamics and binding kinetics of bacteriophage T7 gene protein, gp2.5, and its deletion mutant lacking 26 C-terminal residues, gp2.5-26C. Single-stranded DNA binding proteins which stabilize ssDNA relative to dsDNA are essential for DNA replication in all living systems. Bacteriophage T7 gene 2.5 protein (gp2.5), encoded by gene 2.5 of the bacteriophage T7, is a single-stranded DNA binding protein that binds to and stabilizes transiently formed regions of ssDNA. The factor gp2.5 physically interacts with both T7 DNA polymerase and with T7 helicase/primase and plays multiple roles in T7 DNA replication and recombination in phage-infected cells. It forms a stable homodimer in solution and has a core that is well adapted for interactions with ssDNA and a highly acidic C-terminal tail. This tail is required for dimer formation and for interactions with other replication proteins of the bacteriophage T7 replication system. Its deletion mutant, lacking the C-terminal 26 residues, gp2.5-26C, binds ssDNA more tightly than the full length protein. To this end, force-extension relations at the overstretching transition of dsDNA in the presence of gp2.5 and gp2.5-26C are conducted using optical tweezers microscopy. [Preview Abstract] |
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D1.00017: Proposed Mechanisms of cellular uptake of LDL-DNA complexes Juan Guevara, Troy McWhorter, Natalia Guevara Low-density lipoproteins, LDL, have been shown to be natural vehicles for transport and delivery of exogenous genetic materials to the cell nucleus. The process involves binding of LDL and nucleic acids, binding of the complex to a receptor, endocytosis, release of complex, and translocation to nucleus. Understanding of LDL function in gene delivery may provide insights into mechanisms of infectious diseases and cancer metastasis. However, it has not been studied extensively, and needs phenomenological description, as well as structural basis. The main focus of this study is to determine the fate of LDL-DNA complexes after cell entry. Using fluorescence microscopy, we confirm three possible outcomes of LDL-DNA endocytosis: an endosome/lysosome fusion, co-transit of LDL and DNA to the nucleus, and dissociation of LDL-DNA complex followed by DNA translocation to the nucleus (perhaps mediated by another DNA carrier). We propose that each step in the delivery process is mediated by Lysine- and Arginine-rich motifs located within nucleic acid-binding domains, receptor ligand motifs, and nuclear localization signal sequences of apo B100 and apo E, characteristic proteins of LDL. Similar motifs are abundant in proteins of Dengue viruses 1-4. Comparison of primary and tertiary structures of these unrelated families of proteins suggests that the mechanisms for LDL-mediated cell entry of DNA are similar to the process utilized by viruses in intracellular delivery of their genetic material. [Preview Abstract] |
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D1.00018: Bacterial Pili mechanics and dynamics at the Nanoscale Glenn Grissom, Ahmed Touhami The adhesion of bacteria to surfaces plays an important role in disease, providing the critical first step in the biofouling of a surface and in biofilm formation. Initial stage of adhesion involves thin appendages called pili present on the surfaces of many gram-negative bacteria. The aim of the present study is to determine the molecular forces required to evaluate adhesiveness of type I and type IV Pili to substrata. The adhesiveness of single bacteria cell to substrata as a function of pili expression are investigated using an AFM cantilever as a force transducer. This work is particularly innovative in that, for the first time, the extension and retraction dynamics of a single pilus are monitored by fluorescence and simultaneously the adhesion force are assessed by AFM force spectroscopy. Insight gained from this study of this simple model system will be applicable to more complex bacterial pathogens and will enhance our ability to inhibit their adhesion to surfaces. [Preview Abstract] |
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D1.00019: Exploring the Membrane Association Behavior of Beta-Amyloid Protein Using Multiscale MD Simulations Yiyi Cao, Sara Cheng, Campbell Compton, Hoa Nguyen, K. Cheng Interactions of beta-amyloid (A-beta) protein with lipid membranes have been linked to Alzheimer's disease (AD). At present, the mechanisms of A-beta/lipid interactions remain unclear. Using a multiscale molecular dynamics (MD) simulation technique, we have investigated the membrane-association behavior of A-beta in a lipid bilayer. The protein was initially in a gamma or alpha state and associated with the membrane surface. The protein in the gamma state was mostly in random coil. However, the protein in the alpha state comprised of alpha-helix and random coil structures and with the hydrophobic lipid insertion domain embedded in the lipid hydrocarbon region. Using a coarse-grained (CG) MD simulation, the gamma state detached from while the alpha state remained attached to the membrane. Applying a reverse mapping (CG to atomistic) procedure and a subsequent atomistic simulation, the alpha state still remained attached to the membrane. We propose that the association of the lipid insertion domain with the hydrocarbon region of the membrane is important to stabilize the membrane association behavior of A-beta. This membrane associate behavior might play a key role in the self-aggregation of A-beta on the 2D membrane surface that eventually lead to AD. [Preview Abstract] |
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D1.00020: Molecular Dynamics Study of Phthalocyanine and Sulfonated-Phthalocyanine and C60 Interface Carlos Diaz, Marco Olguin, Tunna Baruah, Rajendra Zope Organic photovolatics (OPV) hold promise as cheap large-area technology for power generation.~The fundamental mechanism of power conversion in~OPV is dominated by interfacial processes such as~charge transfer and charge separation.~The energetics and dynamics of these processes depend on the morphology of the donor and acceptor (DA) interfaces.~In experiments, these DA complexes are usually deposited on metal surfaces using spin coating or similar technique.~To understand the morphology of interface and growth of the OPV on surface,~we use molecular dynamics~simulations with various layers of phthalocyanine and sulfonated phthalocyanine molecules on a Ag(111) surface. We examine the~effect of sulfonation on the morphology of thin films. By introducing the acceptor molecules such as C60 in~various~concentrations we examine the variation in the morphology of OPV films with the different forms~of phthalocyanine surfaces. We then select a few configurations of the DA complexes from the molecular~dynamics trajectories and~determine the charge transfer energies and the transport gap at the quantum mechanical~level. Finally, by~averaging over the configuration we obtain insights into the charge transfer energetics~and the energy level alignments at the organic DA interface. [Preview Abstract] |
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D1.00021: A comparison of methods to characterize non-stationarity in time series data Robert Stone, Soma Mukherjee In this work we examine methods to characterize a time-dependent noise background of time series data generated by the Laser Interferometer Gravitational wave Observatories (LIGO). This non-stationarity originates from both instrumental and environmental noise, and can be exhibited by sharp transient features in the data as well as by slowly-varying statistical properties. The efficient identification of the presence of non-stationarity can have the net effect of increasing the sensitivity of the detectors. We present the results of various methods we applied to characterize the non-stationarity of the data, including machine-learning approaches. These methods have exhibited significant overlap with results generated by standard LIGO data monitoring tools. [Preview Abstract] |
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D1.00022: Dilution factor measurement for a vibrating steel string Moises Castillo, Gianpietro Cagnoli, Mario Diaz Measurements of mechanical losses have been done in the past in configurations parallel and perpendicular to the gravitational potential of earth with different sample shapes. Gravity will modify the quality factor of resonances when the restoring force depends on it, like in a pendulum, because of the conservative nature of the gravitational field. The configuration used in this experiment involves a steel string under tension. The restoring force will be due to the rigidity of the string and tension rather than gravity. The goal is to quantify the relation between the tension of a steel string and its quality factor for varied resonant modes and to demonstrate that the tension of the string works like a conservative field for the string dynamics. [Preview Abstract] |
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D1.00023: Properties of Gold Thin Films Sputtered on Glass Lindsay Bechtel, Chris Tanner, Andra Troncalli, Mikhail Kozlov When gold thin films have a thickness below 100 nm they begin to have different optical and electrical properties than bulk gold. In our project we deposited thin films of gold by sputtering onto glass. We made a set of 12 thin films ranging from 2 to 50 nm. These films were characterized through AFM measurements and transmittance spectroscopy. We will discuss the optical properties at various wavelengths for each film. [Preview Abstract] |
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D1.00024: Monoclinic RbD$_{2}$PO$_{4}$: room temperature synthesis, chemical and structural stability upon heating Cristian Botez, Masoud Mollae, Andres Encerrado Manriquez, Michael Eastman Monoclinic RbD$_{2}$PO$_{4}$ polycrystals (DRDP) were synthesized via the room tempearture crystallization of RbH$_{2}$PO$_{4}$ (RDP) dissolved in D$_{2}$O. Powder x-ray diffraction (XRD) data collected at T$=$25$^{\circ}$C indicate that this deuterated compound crystallizes in spacegroup P2$_{1}$/m with unit cell parameters a$=$7.688{\AA}, b$=$6.192{\AA}, c$=$4.781{\AA} and $\beta =$109.02, and is \textit{isomorphic} with the intermediate-temperature phase of its hydrogenated counterpart RDP. We found no evidence of previously reported [\textit{Phase Transitions} \textbf{80}, 17 (2007)] polymorphic phase transition in DRDP upon heating from room temperature to 210$^{\circ}$C. All lattice parameters vary smoothly within this temperature range, demonstrating that the P2$_{1}$/m phase persists upon heating. In addition, the unit cell volume of monoclinic DRDP is $\sim$ 1{\%} greater than that of its RDP polymorph at all temperatures between 150$^{\circ}$C and 210$^{\circ}$C, which indicates the absence of significant deuterium-hydrogen isotope exchange. Further heating to 240$^{\circ}$C leads to the thermal decomposition of the title compound via dehydration. [Preview Abstract] |
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D1.00025: Two Dimensional Transition Metal Dichalcogenides Synthesis and Exfoliation Marina Paggen, Kanokporn Chattrakun, Brian LeRoy Transition metal dichalcogenides (TMDCs) are layered crystals that can be exfoliated to a monolayer while maintaining their electronic properties. Since the demand for high performing smaller electronic components is on the rise, the ability for the compounds to maintain electronic properties at the atomic level makes them appealing for various state-of-the-art applications. However, most TMDC compounds are not naturally abundant and must be synthesized in order to evaluate their electronic properties. An efficient and reliable method is required to synthesize the TMDC material. To determine the best techniques, methods of crystal synthesis and exfoliation were coupled to see which materials were best suited for this process. The chemical vapor transport method and sublimation methods were successful synthesis procedures and consistently created layered structured crystals. Micromechanical cleavage is the cleanest and simplest method for exfoliating monolayers. The compounds evaluated through this process were two semiconductors: tungsten disulfide and tungsten diselenide, as well as a superconductor: tantalum disulfide. For the semiconductors, photoluminescence was used to determine the number of layers and confirm the direct bandgap in exfoliated monolayer samples. For all compounds, atomic force microscopy was used to confirm the number of layers once exfoliated. All materials exhibit a potential for clean synthesis through mechanical exfoliation, simplifying the process to synthesize samples for TMDC research. [Preview Abstract] |
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D1.00026: X-ray Diffraction Study of Acetaminophen Victor Gonzalez, Leonel Griego, Andres Encerrado, Cristian Botez Acetaminophen is one of the most common active ingredients in pharmaceutical products. Its crystal structure might change if it is not stored correctly. We analyzed the crystal structure of acetaminophen to observe if it changes upon heating. Pharmaceutical products usually need to be stored carefully, which includes keeping them in a dry and cool place. If acetaminophen were to be exposed to high temperatures when stored improperly, its crystalline structure may be affected; therefore, changing its biological properties. We prepared our powder samples by crushing two 500mg tablets of Equate{\textregistered} and collected diffraction data on a Siemens{\textregistered} D5000 X-ray diffractometer at temperatures between 25$^{\circ}$C and 165$^{\circ}$C. We analyzed each data set by carrying out full-profile (Le Bail) refinements starting with the known room-temperature lattice parameters a$=$ 11.72 b$=$9.379 c$=$7.106 $th =$97.472, and space group p2$_{1}$/n of acetaminophen. Our data and analysis reveal that the lattice parameters vary smoothly within the 25 -- 165$^{\circ}$C temperature interval, which indicates that no polymorphic phase transitions occur. Further heating above 165$^{\circ}$C leads to the thermal decomposition of the active ingredient. [Preview Abstract] |
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D1.00027: Density Increasing in Special Theory of Relativity Florentin Smarandache According to the Special Theory of Relativity the mass of a moving object increases with the speed of the object with the factor $F(v)=\frac{1}{\sqrt {1-\frac{v^{2}}{c^{2}}} }$, but what really increases: the object density, the object volume, or both? Because~~ \textit{Mass }$=$\textit{ Volume }$\times $\textit{ Density }for homogeneous bodies, and since the object length decreases (in the direction of movement), then should we understand that the object volume also decreases? The volume decreases with the contraction factor $C(v)=\sqrt {1-\frac{v^{2}}{c^{2}}} $ , hence the density increases with$F^{2}(v)$ Then the \textit{Mass-Increasing Factor} is equal to $F(v)$ Yet, Einstein himself disliked the concept of relativistic mass given by the formula: \[ M(v)=\frac{m}{\sqrt {1-\frac{v^{2}}{c^{2}}} } \] where $m \quad =$ rest mass, and $M \quad =$ relativistic mass of the object moving at speed $v$. [Preview Abstract] |
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D1.00028: On the Fluid Dynamics Nature of General Relativity and Estakhr's Fluid Field Geodesic Equation Ahmad Reza Estakhr EFFG (Estakhr's Fluid Field Geodesic) Equation is developed analogy of Einstein's Field Equation and EMG (Estakhr Material-Geodesic) Equation (Which is developed analogy of Navier-Stokes Equations and Einstein Geodesic Equation ref:1) by EMG equation $\frac{DJ^{\mu}}{D\tau}=J_{\nu}\Omega^{\mu\nu}+\partial_{\nu}T^{\mu\nu}+\Gamma^{\mu}_{\alpha\beta}J^{\alpha}U^{\beta}$ we can find EFFG equation $\frac{DJ^{\mu}}{D\tau}=J_{\nu}\Omega^{\mu\nu}+\frac{c^4}{8\pi G}\partial_{\nu}(R^{\mu\nu}-\frac{1}{2}g^{\mu\nu}R+g^{\mu\nu}\Lambda)+\Gamma^{\mu}_{\alpha\beta}J^{\alpha}U^{\beta}=0$ Where $R^{\mu\nu}$ is Ricci Curvature tensor, $R$ the scalar Curvature, $g^{\mu\nu}$ the metric tensor, $\Lambda$ is cosmological constant, $G$ is gravitational constant, $c$ the speed of light in vacuum, $T^{\mu\nu}$ the Stress-Energy tensor, $J^{\mu}$ is four-current mass density, $J_{\nu}\Omega^{\mu\nu}$ is Material derivative, $U^{\mu}$ four-velocity field and $\Gamma^{\mu}_{\alpha\beta}$ is Christoffel symbol. ref 1: http://meeting.aps.org/Meeting/DFD13/Session/R8.4 [Preview Abstract] |
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D1.00029: Ground and excited state properties of dye attached fullerenes Amanda Garnica, Marina Paggen, Rajendra Zope, Tunna Baruah C$_{60}$ fullerene and its derivatives are the most popular acceptors which are used in molecular/polymeric complexes used in organic photovoltaics. We have studies C60 molecule functionalized with two dye molecules: DPP and TBTDT. Using density functional theory and large polarized all electron Gaussian basis, we optimized the structures of the C$_{60}$-DPP and C$_{60}$-TBTDT molecules. The electronic structure of C$_{60}$ changes upon functionalization with the dye molecules. The electron affinity of the functionalized fullerene increases. The optical spectra of the functionalized molecules will be presented. Inspection of molecular orbitals of these systems indicates that the HOMO level is localized on the dye whereas the LUMO is on the C$_{60}$ molecule. We have also calculated several lowest CT excited states where the charge transfer takes place from the HOMO on the dye to the LUMO on the C$_{60}$ molecule. [Preview Abstract] |
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D1.00030: Magnetic properties of positive and negative charged superparamagnetic nanoparticles Gamage Dannangoda, Karen Martirosyan, Boris Ermolinsky Magnetic iron oxide nanoparticles particularly well known drug-delivery vehicles since their surfaces can be easily modified with antibodies to target specific receptors on tumor cells. The advantages of specific properties of superparamagnetic magnetic nanoparticles can be used as magnetic responsiveness and magnetic imaging. In this report we studied magnetic properties of positive and negative charged magnetite Fe3O4 nanoparticles. The electrical potential of the particles were varied from -33 mV up to 45 mV. Saturation magnetization and coercivity were obtained from the hysteresis loops at room temperature and 5K under a maximum applied field of 9T. The higher saturation magnetization for positive particles was Ms$=$53 emu/g at 300K compared to negative particles (Ms$=$25emu/g at 300K) could be the effect of higher mean particle size or higher grain size of magnetization of positive charged particles. Zero-field-cooled (ZFC) and field-cooled (FC) magnetization curves were measured in the temperature range of 1.9-300K using magnetic field of 100Oe. Zero coercivity and remanent magnetization and merging point indicate that the particles are superparamagnetic at the room temperature. [Preview Abstract] |
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D1.00031: Thermogravimetric and magnetic characterization of solution combustion synthesized YFe2O4 Shangir Siddique, Mkhitar Hobosyan, Chamath Dannangoda, Karen Martirosyan YFe2O4 has interesting magnetic properties which are sensitive to the crystalline size of particles. The rare-earth ferrites similar to YFe2O4 are widely used in fuel cells, catalysts, gas sensors, magnetic materials, and environmental monitoring application. Yttrium ferrite exhibits soft magnetic properties which can be used in devices with high frequency applications. Recent studies also show that it has electrical and magnetic coupling, and shows ferroelectricity near the ferrimagnetic transition temperature around 250 K. It is also a multiferroics, and displays more than one primary ferroic order parameter simultaneously. We prepared YFe2O4 by solution combustion synthesis, using Y(NO3)3 x 6H2O, Fe(NO3)3 x 9H2O and glycine NH2CH2COOH, that were dissolved in distilled water. The mixture was gradually vaporized during heating at 250 $^{\circ}$C. The produced soft foam then was ignited and a light brown fluffy product was received. We analyzed the solution combustion of ferrite by thermo-gravimetric analysis to understand the mechanism of interaction, as well as characterized the combustion products by XRD and measured magnetic properties over the temperature range from 1.8K to 300K with PPMS. According to TGA results, the decomposition of the nitrides starts at around 150 $^{\circ}$C. The exothermic interaction begins at 200 $^{\circ}$C. The product has good magnetic properties. The saturation magnetization began at a magnetic force of 3100 Oe, with magnetic moment of 34 emu/g, and at 1000 Oe the magnetic moment is 24 emu/g. [Preview Abstract] |
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D1.00032: An Empirical Model for Subwavelength Diffraction in Silicon Nano-Patterned Membrane Anton Gribovskiy, Malik Rakhmanov Nano-patterned membranes or two-dimensional photonic crystal slabs promise many applications in silicon nanophotonics. They can be used as highly efficient broadband reflectors or narrowband filters in silicon integrated circuits. These applications are based on interaction between the radiation field and the guided modes in the slab. The associated subwavelength diffraction in the reflected light was experimentally observed for 1064 and 1550 nm wavelengths. In this work we introduce an empirical model to explain this subwavelength diffraction and its polarization properties. The model is built in terms of periodic waves excited in the slab by the incident light. The study of the empirical model is backed by the FDTD simulations of light scattered by the reduced size nano-patterned membrane. By varying the periodicity of the in-plane waves, their amplitudes and phases we achieve agreement with experiment. [Preview Abstract] |
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D1.00033: Cs-Corrected STEM Characterization of Pt-Pd Polyhedral Core-Shell Nanostructures Subarna Khanal, Gilberto Casillas, J. Jesus Velazquez-Salazar, Miguel Jose-Yacaman Pt-Pd core-shell nanoparticles have been found to possess significant applications in fuel cells, ethanol and methanol oxidation reactions, hydrogen storage, etc. However, the cost of Pt makes it unpractical to use in big quantities; therefore, one of the big challenges is to very small catalysts with only a few layers of the active metal in the shell in order to maximize the efficiency in their use. In this work a facile synthesis method was used to synthesize Pt-Pd core-shell nanoparticles in the size range of 20 nm and characterized them by Cs-corrected scanning transmission electron microscopy. This technique allowed us to probe the structure at the atomic level of these nanoparticles revealing new structural information. We determined the structure of the three main polyhedral morphologies obtained in the synthesis: octahedral, decahedral and triangular plates. In addition the STEM energy dispersive X-ray spectroscopy (EDS) chemical analysis can be better identified the chemical composition of the nanocrystals. The overgrowth of the thin Pd shells on the Pt cores due to the epitaxial growth modes was observed. In this work, we have been able to observed Shockley partial dislocations, stacking faults, kinks and adatoms at the surfaces of the nanoparticles. [Preview Abstract] |
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D1.00034: Electrochemical performance characterization of nanostructured LiCoO$_{2}$ David Garza, Karen Martirosyan, Mkhitar Hobosyan, Yerkezhan Mamyrbaeva The theoretical capacity of LiCoO$_{2}$ is 300 mAh/g and practical capacity is significantly lower (150 mAh/g) than theoretical value since concentration polarization occurs within the particle before the entire capacity can be utilized. In general, reducing the particle size of electrode materials in lithium-ion batteries to nano domain level overcome this problem. Nanoscale dimensions will provide a short path for the ion motion in the ionic solid electrodes. Therefore, reactions become faster and batteries can be charged and discharged rapidly. In this report we describe the behaviour features of the electrochemical performance of lithium ion battery electrod material (LiCoO$_{2})$ produced by Carbon Combustion Synthesis of Oxide (CCSO). The custom-made pouch-type battery was prepared. The battery was assembled in glove box using separator membrane with special type of polyethylene. The charge-discharge cycles were carried out in the potential range of 2.7-4.2 V using 8-channel battery analyser. The specific capacity had initial value of 200 mAh/g and after 30 cycles the capacity dropped to almost 180 mAh/g retaining over 90 {\%} of initial capacity. This result is confirming that CCSO synthesized ultrafine LiCoO$_{2}$ has stable structure and gives opportunity to extract more than 66 {\%} of theoretical capacitance. [Preview Abstract] |
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D1.00035: Role of apparent spatial periodicity of metal film and \textit{ac} electric field on the surface plasmon resonance and interference effects in nematic liquid-crystals Kunal Tiwari, Blake Barnett, Suresh Sharma It is well known that travelling surface plasmon polaritons (SPPs) can be generated by using Kretschmann geometry, in which a sample (in this case a nematic liquid crystal E44) is sandwiched between thin noble-metal film coating ($\sim$25 nm thick) on the base of high-index prism and Indium-Tin-Oxide coated glass slide [1,2] The onset of SPPs is evidenced by loss in the intensity of totally reflected $p-$polarized light at a certain angle greater than the critical angle for total internal reflection. Recently, we have observed interesting interference effects and changes in the plasmon resonance, which appear to be related to the spatial periodicity of the metal film and field-induced changes in the refractive index of the liquid crystals. \\[4pt] [1] K. Tiwari, A. K. Singh, and S. C. Sharma, Appl. Phys. Letts. \textbf{101}, 253103 (2012). \\[0pt] [2] K. Tiwari and S. C. Sharma, Effect of applied ac electric field on surface plasmon excitations at metal/liquid-crystal interface, March Meeting of the American Physical Society, 2013, http://meetings.aps.org/link/BAPS.2013.Mar.Q1.180 [Preview Abstract] |
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D1.00036: Comparison of Monocrystalline Nanocubes and Polycrystalline Nanospheres of Fe3O4 Arati Kolhatkar, Chamath Dannangoda, Ivan Nekrashevich, Dmitri Litvinov, Richard Willson, Karen Martirosyan, Randall Lee This report describes synthesis of monocrystalline Fe3O4 nanocubes and polycrystalline nanospheres with tunable body diagonals and diameters via solvothermal and thermal decomposition reactions. The dimensions of the spherical MNPs were tuned to obtain particles for one set of spherical MNPs the volume was equivalent to that of a targeted cubic MNP volume and for a second set of spherical MNPs the diameter was equivalent to the body diagonal of a targeted batch of cubic MNPs. The PPMS was used to compare the magnetic properties of the synthesized spherical and cubic Fe3O4 MNPs on a volume and diameter/body diagonal basis. As compared to polycrystalline nanospheres, there is a higher saturation magnetization for nanocubes, which makes them more attractive for biosensing applications. The synthesized nanocubes also have a significantly higher coercivity as compared to their nanospherical counterparts with the same volume or equivalent diameter. This makes them more suitable for hyperthermia applications in which the heat generated varies linearly with coercivity. With this study, we demonstrate that shape is an important parameter that can be used to manipulate nanoscale magnetism in Fe3O4 MNPs in order to tailor them for a particular application. [Preview Abstract] |
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D1.00037: Magnetic Ferrite Encapsulated Nanoparticles for Targeted Drug Delivery Ed Alvarado, Karen Martirosyan Magnetic encapsulated nanoparticles have been in the interest of many researchers due to their impressive applications. One of the major applications of these nanoparticles is their biomedical relevancy. Nanoparticles have been in the center of 21$^{\mathrm{st}}$ century Physics research and since then there have been major improvements that have made particles with more efficient designs and synthesis techniques in order to ensure the drug-delivering component of the Magnetic nanoparticles. The essential component of the nanoparticles is their ability to preform targeted drug delivery and targeted drug therapy that is able to transport the drug directly to the center of the diseased cells and therefore treat it deliberately without causing any repercussions to the healthy cells in the body. The nanoparticles themselves are designed with a polymeric shell loaded that is injected with an anti-cancer drug called quercetin that targets lung cancer cells. Their structure is composed of mixed oxide particles such as magnetite Fe3O4 and ferrites CoFe2O4 and NiFe2O4. [Preview Abstract] |
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D1.00038: Another Superluminal Thought Experiment Florentin Smarandache Suppose we have two particles $A$ and $B$ that fly in the opposite direction from the fixed point $O$, with the speeds $v_{1}$ and respectively $v_{2}$ with respect to an observer that stays in the point $O.$ Let's consider that $v_{1} + v_{2} \ge c.$ \begin{itemize} \item But, an observer that travels with particle $A$ (therefore he is at rest with particle $A)$ measures the speed of particle $B$ as being $v = \quad v_{1} + v_{2} \ge c.$ \end{itemize} Similarly for an observer that travels with particle $B$: he measures the speed of particle $A$ as also being superluminal: $v = \quad v_{1} + v_{2} \ge c.$ \begin{itemize} \item If we suppose $v_{1} = c$ and $v_{2}$\textit{ \textgreater 0}, then for the observer that travels with particle $A$ his speed with respect to observer in $O$ is $c$. But, in the same time, for the observer that travels with particle $A$ his speed with respect to particle $B$ should be greater that $c$, otherwise it would result that particle $B$ was stationary with respect to observer in $O$. It results that $c + v_{2}$\textit{ \textgreater c }for non-null$ v_{2}$, contrarily to the Special Theory of Relativity. \end{itemize} [Preview Abstract] |
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D1.00039: Improving Trigger Timing Lacey Medlock SeaQuest (Fermilab 906) is a fixed-target experiment that uses the 120 GeV Fermilab Main Injector to collide protons with stationary targets. One of its primary goals is to study the ratio of anti-down to anti-up quarks that exist in the proton via the Drell-Yan process, in which an anti-quark and quark annihilate into a photon that then decays into a pair of muons. A previous Fermilab experiment, E866/NuSea measured this asymmetry and indicated possible surprising behavior when the anti-quark in a proton carries a larger fraction of its momentum. SeaQuest will investigate this behavior. The SeaQuest detector relies on plastic scintillators to provide signals to know when a particle goes through the detector. The scintillators are up to 72" in length and thus can give signals that last 20-25 ns, which is an issue because protons arrive every 18.9 ns. This gives a possibility of confusion of scintillator signals from two different proton collisions.In order to reduce the pulse length and in turn the number of missed events, we attached short wires that reflect an inverted pulse due to an impedance mismatch via an attached resistor. The wires make the signal length short enough to resolve this problem. These short wires with resistors are referred to as clip lines, which were constructed and installed on all scintillation detectors in the SeaQuest experiment. [Preview Abstract] |
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D1.00040: Development of Handheld Detector for Neutron Tagging William Baker, Caitlin Campbell The Cryogenic Dark Matter Search (CDMS) collaboration is in need of a cheap, efficient device for neutron veto/tagging for use in conjunction with its Si/Ge detectors. We have conceived of the idea of using plastic scintillators, with Gd (neutron capture cross section $=$ 2.6E5 barns) loaded polyvinyltoluene and photodiodes to detect thermal neutrons. The device is light weight (\textless 5 kg) and is shielded by polyethylene to thermalize higher energy neutrons for capture in the Gd loaded plastic. The capture by-products will be shifted to the UV-visible spectrum by the scintillating material, and then detected by high sensitivity photo-diodes. In addition, the device has the ability to discriminate against radioactive gammas, to avoid false positives. The device also provides a proof of principle for neutron veto (screening) around low background experiments, such as the CDMS experiment, where the basic principle can be applied in a multi-layer form to significantly enhance the neutron tagging so important for such low background experiments. [Preview Abstract] |
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D1.00041: Three Dimensional Spatial Recognition Mapping of Magnetic Fields Utilizing Commercial Commodity Hardware Francisco Lozano A three dimensional portable tracking system can be developed using the relatively cheap commodity hardware known as the Wiimote. The Wiimote can be used to track position data, and can be coupled with data from other instruments. This research aims to integrate position and magnetic field strength data to build a virtual map of surrounding magnetic fields. [Preview Abstract] |
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D1.00042: Report on Experimental Upgrades of Phonon Imaging Apparatus Used in Measurements of Ballistic Phonons through Superconducting Sn Crystals Francisco Teran, Tim Head This presentation discusses work done to upgrade the performance of a phonon-imaging apparatus. Fabrication and testing of a sample holder used to perform the experiment, and the creation of C{\#} programs to interface galvo-mirrors through a D/A convertor is discussed. We performed a preliminary phonon imaging experiment with a 1mm single crystal sample of Sn, but recorded no measurable ballistic phonon flux. [Preview Abstract] |
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D1.00043: Construction of Prototype B for the COMPASS Collaboration James Mallon While there has been significant progress in the past years of understanding the quark and gluon structure of the nucleon, many important questions remain open; in particular, we have only elementary understanding of the origin of the proton spin. The COMPASS project is a fixed-target nuclear physics experiment at CERN which explores the internal structure of the proton. ~COMPASS II's polarized Drell-Yan measurements will be exploring the quark angular momentum contribution to the spin of the proton by studying quark-antiquark annihilation. Several drift chambers must be constructed to replace older, faulty straw chambers. Smaller prototype drift chambers were constructed, one in Saclay, France, and the other Prototype B (PTB), at the University of Illinois at Urbana-Champaign. PTB is 16.5'' wide, 72'' long, and 3.03'' tall, with 66 wires across two separate wire planes. This poster will detail the methods used to fully assemble PTB. [Preview Abstract] |
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D1.00044: Cell Elasticity-based Microfluidic Isolation of Metastatic Tumor Cells Muhymin Islam, Samir Iqbal, Young-tae Kim Circulating tumor cells (CTCs) have significant diagnostic value for cancer patients. We report a label-free, simple and rapid microchannel filter type device for isolation of metastatic cancer cells based on their mechano-physical properties like size and deformability. The microdevice fabricated in polydimethylsiloxane (PDMS) using soft-lithography contained one inlet and one outlet connected via 400 microchannels. It was observed that metastatic renal cancer cells, derived from real patient's brain tumor were highly elastic and squeezed through microchannels much smaller than their sizes. Using a reverse-selectivity approach, the number of microchannels and their dimensions were varied to optimize and reduce the shear stress on tumor cells such that these did not pass through filtering channels. Consequently, the cancer cells were collected with an efficiency of more than 78{\%} using channels with cross section area of 5 $\mu$m x 5 $\mu$m. Eventually tumor cells were mixed with blood and successfully isolated. The microfluidic channel device did not require pre-processing of blood (except dilution) or tagging/modification of cells. [Preview Abstract] |
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D1.00045: Strain Degradation Study of In Situ MgB2 Wire Nathaniel Glaser Accelerator-driven subcritical fission in a molten salt core (ADSMS) offers a double-edged solution to both the nation's diminishing energy resources and accumulation of nuclear waste. The design for this next step in energy and environmental sustainability implements a strong focusing cyclotron (SFC) and, in the scope of this project, a quadrupole component. For the SFC quadrupole to appropriately focus the clusters of accelerated particles, a certain current density must travel through a coiled conductor of a specific geometry. However, the characteristics of the focusing depend largely on the conductor. To generate the appropriate magnetic field gradient and to comply with the geometric constraints of the SFC quadrupole, MgB2 wire was selected as the potential candidate that would best optimize the operational parameters (light cryogenic load, high current density, and degree of structural flexibility). This project developed the testing procedures for the viability of in situ (wind and react) MgB2 within the design constraints of the quadrupole. Methods by which to apply controlled degrees of strain across lengths of wire and methods by which the degradation mechanism of the wire segments could be analyzed through visual and performance metrics were developed. [Preview Abstract] |
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